Somewhat useful debugging messages are available. The choice of
messages is controlled by a bitmap. This may be specified as a
module argument (kernel command line argument as well?), changed
dynamically using an ioctl (not yet) or changed by sending the
string "Dxxxx" to VCI 1023 (where x is a hex digit). See the file
<file:drivers/atm/ambassador.h> for the meanings of the bits in the
mask.

When active, these messages can have a significant impact on the
speed of the driver, and the size of your syslog files! When
inactive, they will have only a modest impact on performance.